arXiv subjects

Karim Elyaouti

Publications and source records attributed to Karim Elyaouti.

5 recordsLinked to original sources

arXiv2026

Full Next-To Leading-Order Electroweak and QCD Corrections to the Relic Density in the CxSM

In this work, we present the calculation of the next-to-leading order (NLO) QCD and electroweak corrections to the thermally averaged cross section of Dark Matter (DM) annihilation in the framework of the complex singlet extended Standard Model (CxSM) with one DM candidate. We derive the corresponding NLO QCD and electroweak corrected relic density and discuss the impact of the corrections as well as the remaining theoretical uncertainty due to missing higher-order corrections. This is estimated through a variation of the renormalization schemes for the singlet vacuum expectation value $v_S$ and the Higgs mixing angle $α$. For the bulk of the scanned parameter points, the QCD and electroweak corrections are found to be of typical size with the remaining theoretical uncertainty ranging at the percent level. The larger corrections that are found, can be attributed to a large counterterm for $v_S$ emerging in the case of large mass gaps in the decay channel used for the renormalization. The corrections are of phenomenological impact. There are parameter points that are allowed at leading order (LO), but are excluded after including the NLO corrections to the relic density, and vice versa. Our corrections have been implemented in the new code RelExt@NLO based on the LO code RelExt, which has been made publicly available. This work marks a first step towards the calculation of the QCD and electroweak corrected relic densities in models with DM candidates stabilized by a discrete $\mathbb{Z}_2$ symmetry.

hep-ph↗

arXiv2026

NMSSMScanner: Efficient Scans in the NMSSM Parameter Space Proof of Concept

We present the first version of the new scanning tool NMSSMScanner that allows to perform efficient scans in the complex multi-parameter space of the Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) while taking into account all relevant constraints. As a proof of concept we apply it to the search for NMSSM parameter configurations that maximize Higgs boson pair production from resonant scalar or pseudoscalar production in various final states.

hep-ph↗

arXiv2026

RelExt: A New Dark Matter Tool for the Exploration of Dark Matter Models

We present the C++ program RelExt for Standard Model (SM) extensions that feature a Dark Matter (DM) candidate. The tool allows to efficiently scan the parameter spaces of these models to find parameter combinations that lead to relic density values which are compatible with the measured value within the uncertainty specified by the user. The code computes the relic density for freeze-out (co-)annihilation processes. The user can choose between several pre-installed models or any arbitrary other model featuring a discrete $\mathbb{Z}_2$ symmetry, by solely providing the corresponding FeynRules model files. The code automatically generates the required (co-)annihilation amplitudes and thermally averaged cross sections, including the total widths in the $s$-channel mediators, and solves the Boltzmann equation to determine the relic density. It can easily be linked to other tools like e.g.~ScannerS to check for the relevant theoretical and experimental constraints, or to BSMPT to investigate the phase history of the model and possibly related gravitational waves signals.

hep-ph↗

arXiv2026

Reassessing CP Violation in the C2HDM with Machine Learning

We provide a study of the parameter space of the complex 2-Higgs Doublet Model (C2HDM), focusing on signs of large CP-violating couplings of the 125 GeV Higgs boson with the fermions. The study is performed utilizing Machine Learning (ML) techniques developed recently for parameter space exploration, including an Evolutionary Strategy Algorithm and Novelty Reward. We give particular attention to the electron electric dipole moment (eEDM). We confirm that the recently found kite diagrams are crucial for the outcome of the analysis. Moreover, their use also mitigates the dependence of the results on the scale and scheme choice of the masses in the loop diagrams. We furthermore point out that, already at the current level of experimental precision, the Barr-Zee diagrams with charm quark loops must be taken into account. The combined use of kite diagrams and ML techniques allows for the resurrection of large fermion CP-odd couplings for Type-II and Flipped C2HDM when the 125 GeV Higgs coincides with the second lightest neutral scalar. This arises due to cancellations, typically of the per-mil order, which, moreover, will still be possible for a foreseeable eEDM precision down to $10^{-33}$ e.cm. For these cases, the constraints on the CP-odd couplings arises from the precision LHC measurements.

hep-ph↗

arXiv2024

Freeze-in as a Complementary Process to Freeze-Out

There are many extensions of the Standard Model with a dark matter (DM) candidate obtained via the freeze-out mechanism. It can happen that after all experimental and theoretical constraints are taken into account, all parameter points have a relic density below the experimentally measured value. This means that the models solve only partially the DM problem, and at least one more candidate is needed. In this work we show that it is possible to further extend the model with a DM candidate obtained via the freeze-in mechanism to be in agreement with the relic density experimental measurement. Once the relic density problem is solved with this addition, new questions are raised. This new model with at least two DM candidates could have a freeze-out undetectable DM particle both in direct and indirect detection. This could happen if the freeze-out DM particle would have a very low density. Hence, a collider DM hint via excess in the missing energy with no correspondence in direct and indirect detection experiments, could signal the existence of a Feebly Interacting Massive Particle (FIMP). Conversely, if a DM particle is found and a particular model can explain all observables except the correct relic density, an extension with an extra FIMP would solve the problem. The freeze-in DM candidate, due to the small portal couplings, will not change the remaining phenomenology.

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